In transportation vehicles such as trucks, cars, planes and boats, the on-board fuel tank is generally shaped to maximize fuel storage capacity yet fit within often restricted areas dictated by the surrounding vehicle structure or chassis. Often, known saddle tanks or two distinct storage tanks having generally at least two separate fuel storage chambers are incorporated into the vehicle, see U.S. Pat. No. 5,170,764, to Tuckey and assigned to Walbro Corporation, issued Dec. 15, 1992, and incorporated herein by reference in it's entirety.
Typically mounted in at least one of the two fuel chambers is an electric motor fuel pump commonly used to supply the fuel demand for the at least one engine in the vehicle. The electric fuel pump is known to be integrated into an in-tank fuel pump module typically having a filter at the pump inlet, a check valve at the pump outlet and a pressure regulator, downstream of the outlet check valve, for controlling the pressure of fuel supplied to a fuel rail mounted on the engine and returning excess fuel back to the fuel tank. A support structure of the module usually includes a flange mounted sealably to the fuel tank and a reservoir can is typically part of the module. The fuel pump is usually located in the reservoir can and draws fuel therefrom. The reservoir provides a reliable source of liquid fuel for the fuel pump even when the larger fuel chamber is relatively low of fuel and/or when the fuel within the supply chamber sloshes about due to movement of the vehicle or any other dynamics occurring relative to the vehicle.
A reservoir jet pump typically maintains adequate fuel levels in the reservoir can by routing a minority portion of pressurized fuel from the electric pump outlet and sending it through a venturi tube which in-turn aspirates a much greater amount of fuel from the fuel tank and into the reservoir. Typically the jet pump functions continuously regardless of reservoir fuel level and regardless of the fuel pressure at the pump outlet or pressure at the fuel rail. It is thus common for fuel in the reservoir can to overflow back into the fuel chamber.
In vehicle applications having only one fuel pump, thus drawing fuel from only one of the at least two fuel chambers, a gravity fed syphon or transfer line typically communicates between the two chambers to maintain equal fuel levels and prevent one chamber from dominating another. Unfortunately, in some applications placing a transfer line near or below the bottom of the two fuel tank chambers is not practical due to surrounding vehicle structure or safety concerns. Furthermore, in other applications the two fuel chambers or separate tanks may be located at entirely different elevations, yet maintaining substantially equal volumes of fuel in each tank is still desirable for vehicle maneuvering performance or ballast.
In some vehicle applications having high fuel consumption, such as a truck having a large combustion engine, or a boat or plane having two engines, it is desirable to have an electric motor fuel pump module in each fuel tank chamber, see U.S. Pat. No. 6,371,153, to Fischerkeller, et al, issued Apr. 16, 2002, and incorporated herein by reference in its entirety. Because both fuel pumps must operate reliably, it is imperative that the storage of fuel in one fuel chamber does not dominate over the other chamber and that both chambers have fuel therein at relatively low fuel level or nearly empty conditions.